Allen is the only hurricane in the recorded history of the Atlantic basin to achieve sustained winds of 190 mph (305 km/h),[nb 1] thus making it the strongest Atlantic hurricane by wind speed. Until Hurricane Patricia in 2015, this was also the highest sustained winds in the entire Western Hemisphere.

Vuk, the Saffir-Simpson scale was developed by US meteorologist Saffir in the 1960s based on ‘eyewall’ sustained 1 minute windspeed, then refined by US engineer Simpson in the 1970’s for 10 meter height (essentially three stories tall, the ~roofridge of most two story homes. The ratings are based on likely structural damage to ‘ordinary’ structures (think stick built homes) struck by the eye. A Cat 5 destroys these structures completely (google image Hurricane Andrew Homestead Florida damage for vivid examples). Hence there is no meaningful S-S Cat 6 except for scary PR purposes, no different than there is any tornado rated stronger than an Enhanced Fujita scale EF5 for the same reason. There is no meaningful damge number beyond total destruction.
For what its worth, if a cat 1 is 1x wind energy, a Cat 2 is 10x, a Cat 3 is 50x, a Cat 4 is 250x, and a Cat 5 is >500x. Hence my Wilma Cat 3 survived/derived evacuation rule of thumb: cat 2 we stay as the building is designed for minimum Cat 5 (post Andrew building codes). Cat 3 up, we are outa here.

Worse than the wind, the storm surge from a Cat 5 hurricane will take away 12” of topsoil along with everything that was above it or in it. When Cat 5 Hurricane Iniki hit the south shore of Kauai in 1992, 3 blocks of housing in Poipu totally disappeared, along with hotel swimming pools. We survived in a frame home in a housing area up on a hill, but the first block of houses were blown entirely apart, crashing their debris into the second block of houses, knocking them all to the ground. Fortunately for us, we were in the fifth block of houses. On an island there is no where to run. Pray for the folks in the path of Irma.

http://www.warwickhughes.com/blog/?p=811
Our Cat 5 storms are less intense but the damage done to towns that were hit by it were a lot less than what a Cat 4 could do in the 70s. I came across one example from a Cat 4 rated cyclone nearly 100 years ago that pulled up electricity poles out of the ground and threw them some distance, and this happened a few 100 kms inland. Lets hope that this is just an exaggeration so that “unprecedented” can be trotted out again.

Wind speeds at altitude are irrelevant. Ground wind speeds are what does the damage. Ground wind speeds are what’s actually experienced by people and infrastructure on the ground. Hurricanes need to be rated based on measured wind speeds on the ground, not on modeled figures or readings at altitude.

Then we need to work on creating more robust measuring equipment to get accurate ground-level readings instead of relying on guesses or altitude measurements that don’t reflect what’s actually happening at the surface.

I think it’s a fair given that ground speeds will be much higher for a hurricane that’s got altitude wind speeds of 200 MPH than a hurricane whose altitude wind speed is 120 MPH. At a guess. This is a nasty storm and splitting hairs over whether it’s a Cat 5, 6 or 7 isn’t going to change that in the least.

Debodk, sort of true but very difficult. Don’t be too skeptical. The S-S definition is intentionally sustained winds just outside the eyewall, which is sometimes just 10 miles across. So a narrow measurement target. By the physics law of conservation of momentum, most hurricane measurements will be a significantly lesser windspeed. Your issue is actually with the S-S definition, not the Hurricane Hunter actual measurements and model extrapolations down to the surface. See also my comments upthread for more info.
WUWT is a great place to learn stuff you can then verify elsewhere. My late father commanded the 409th Typhoon Chasers off Guam 1948-1950 after getting military sponsored dual masters degrees in meteorology and electronics (early weather radar). I learned stuff at the kitchen table from him. Just passing some along.

“deebok is the kind of person who would demand you use a rule to measure the distance to the moon”
No. Like me, he/she wants people to be upfront when they compare modern “man-made” events with historical events. I’ve already heard that two Cat 4’s hitting the US is unprecedented but its very unlikely that if Harvey happened 100 years ago that it would be written down as greater than Cat 3.

My buddy at NASA tells me they are using satellites to measure multi-path radio signals which can be correlated to wave height (which they can then convert to wind-speed?). This second statement is subject to my not always reliable memory.

But I believe this is correct.

I’m sure the wave height part is correct, it’s the converting to wind-speed that may be subject to recall error…

My wife would caution you at length about my memory.

I can say it in a completely convincing way, though. If that will help.

The Stepped Frequency Microwave Radiometer (SMRF) is a promising tool for direct measurement of surface winds. This instrument has flown aboard research aircraft for more than 20 years and has finally matured enough to transition to operations. It works by sensing the increase in apparent microwave brightness temperature of the water surface caused by more foam as the wind increases. Because rain in the air column between the airplane and the surface also produces a frequency-dependant contribution to the upwelling microwave radiation, the radiometer needs to look at several different frequencies to correct for the precipitation effect and to deduce rainfall rate as a byproduct.

Laid in supplies today. Water and bread shelves at Publix were already stripped bare. No matter to us, our go bag has a case plus 5 days of freeze dried meals and a small camping stove and cookware. If we stay and are in the path, we fill all the large kithen pots for drinking plus the guest bedroom bathtub for flushing. Gas the cars tomorrow. Make decision on stay/go Thursday night or Friday morning after the cone of uncertainty narrows. We stay if we will experience Cat 2 or less. So far, not even taking the precaution of bringing in balcony stuff, always a pain physically and because clutters the condo inconveniently. No need to do so if less than TS winds expected. The building management will make that call probably Thursday for Friday.
Each successive ensemble has the track a bit more west before turning north. CFAN (Judy Curry’s company) has the adjusted track even a bit west of ECMWF, which has a better track record than GFS. So if that holds, we may experience nothing at all except rain from outermost bands. But Naples, Sarasota, Fort Meyers, Tampa look to be in real trouble on Irma’s dirty side if CFAN is correct. Current CFAN track has Irma then recurving and hitting Orlando as a Cat 1-2 then Daytona Beach as a 1. CFAN called Harvey perfectly.
Keys are going to get clobbered with high certainty. Mandatory evacuation starting 7 am for tourists and 7pm for residents tomorrow with schools closed from tomorrow until further noice. They have to move 80000 people up US 1 (only way out), always a mess. Miami (65 miles south of Ft Lauderdale) will likely have at least TS conditions given Irma’s size. The mayor is already urging people to evacuate known flood prone areas starting Thursday.

Hi Vuk,
I am on the west coast, Venice to be exact, about 1 mile to the Gulf as the crow flies. As I already had my hurricane kit stocked in general I spent yesterday and this morning checking and adding anything I needed. The final prep will be to start adding additional water supplies and to make sure I have cash on hand, probably Thurs. Sat will put everything not tied down inside. Hurricane shutters will wait until Sun as late as possible, only takes about an hour. I am going on the assumption that the ECMWF model will prevail and that there is a very good possibility of a major hit to this area. My prep is focused on living for two weeks without electricity.

Rud is correct, stores are already bare but the big box stores have hurricane plans in operation and we expect there to be constant resupply through Sat. I will be staying home unless the eye wall with winds of over 130 mph are expected to make a direct hit on me. If that looks probable then it is off to the shelter.

Funny thing about Venice, it has never taken a direct hit from a hurricane. We are a little higher in elevation than surrounding areas, we are bordered on the south by a very warm Charlotte Harbor and to the north by a very warm Tampa Bay. Plus, this is an ancient Indian burial ground and supposedly protected by their spirits. Looking back at history, perhaps there is something to that after all.

Hey, Latitude, I did not know you were in the Irma targeted Florida Keyes. So here is a sincere WUWT offer. You evacuate close to Miami (mandatory) we will come pick you up to shelter in our cat 5 building. You get the guest bedroom, and we rearrange the balcony furniture to suit. AW has my private coordinates.
Just laid in plenty of food supplies. If We have to evac our ocean above level in Ft. Lauderdale, you have a free fuel, food, and home ride to our Georgia cabin and back. Least we can do. CtM and AW know how to reach us. Offer is very sincere. And remains open for days. Least we can do.

All the stores pretty much picked over here in Merritt Island too.
If this storm pulls a Donna and cuts across the state there wont be much point in going anywhere. Guess I will put up the shutters and wait,

I see no mention of Camille (1969). It is listed as having peak wind speeds of 175 mph*. The “*” indicates that the true wine speed will never be know because the storm “destroyed all wind-recording instruments across coastal Mississippi.”

Irma has recorded sustained speeds of 185 mph that is 10 mph greater than Camille. We do not know what the maximum sustained speeds of IRMA , anyone can speculate that it is 220 mph when no one was recording.

That is strange I got the headline HURRICANE IRMA – CARRIBEAN BRACES FOR EXTREMELY DANGEROUS STORM. Having read the acticle thoroughly I could not find your quotes. I suggest that you follow CNN which stated this is the highest winds peed recorded for a hurracane in the Atlantic. My understanding is that there has been one higher recorded in the Gulf.

No. Irma is still in the Atlantic. Camille, like Katrina, strengthened only once in the Caribbean. That is a meaningful distinction for the NHC. There are hurricanes that form in the Carribean (Harvey) and Atlantic hurricanes that enter the Carribean (Camille, Katrina), and Atlantic hurricanes that do not (cat 5 Matthew last year tracked up the eastern Florida coast remaining at least 50 miles offshore, finally weakening, whacking and flooding the Carolinas as a Cat 1.

I am a professor. My students have no connection to your quote!!!! So over thanksgiving, I am going to have to start binge watching EVERY teeanage and up movie, with IMDB’s list of quotes and then figuring out the right context to modernize my “student connecting movie quotes”

Actually It is not real hard to watch just my wife gets bored out of her mind and leaves. Time to shelve: “Here’s Johnny, the holy hand grenade, I don’t know Ms Robinson, It’s just a flesh wound, what we have here is a failure to communicate, do you concur, show me the money, there’s no crying in baseball…”

SIgh….I have a sense of things passing out of time into the ol’ bin of history and me with it.

As l suggested 6 days ago, it was Irma that was the one that needed to be watched.
lt looks like it will be hitting southern Florida hard. But l think there is better news for the rest of the SE of USA. The jet stream will be tracking much further south then normal, so leading to a stronger jet stream over the area. So once this hurricane moves into north Florida and further north. There is a good chance this hurricane will weaken quickly if the eye moves inland. But its likely to dump a lot of rain in the process.

The thing is moving very slowly in perfect conditions (for a hurricane) over 29C+ water that is warm down to depth. Should be a great case study on hurricane development and technicals. Super Typhoons in the Pacific are typically stronger than Atlantic cyclones.

We should erect a deep foundationed lamp post near sea level that he has a couple loops in it so you can do a Bill Paxton and Helen Hunt moment being strapped to it and get to watch the eye pass over. Just that the movie Twister probably didn’t get the physical damage to the actors correct, and the hurricane will have surge..but … @J. Philip Petersen but you would then get to actually see wind speeds. Be sure to write your SSN on your arm (and leg and other leg and other arm and torso…)

Looking like it’s a bidding war (for public attention) by some to pick the greatest wind speeds.

If it stays on the forecast track and reaches the Florida Straits, the water there is warm enough that the already “intense” storm could become much worse with wind speeds potentially reaching 225 mph, warned Kerry Emanuel, an MIT meteorology professor.

The 1700AST Forecast from the NHC has it skirting the coast of Cuba Saturday afternoon — which might weaken it a bit. It’s not going to be sponging up a lot of moisture on its South side if it follows that track. But you’re right, the question of where it goes and whether it gains strength if it passes through the Florida Straits and into the Caribbean seems a real concern. If it’s going to hit somewhere on the Gulf Coast, I should think that many folks in urban areas should be thinking about evacuating. I don’t know how long it takes to evacuate large parts of Tampa or even (much smaller) Mobile. But I suspect, it takes way more than 24 hours.

Yes. I’ve always pitied the islanders hit by one of these monsters. Especially places like Haiti that have stripped all of the natural vegetation and will face flooding and landslides after the winds leave.

What I am confused on is the last pressure I saw was 923 it might be lower now. I was always taught that pressure and wind speed were closely correlated. Gilbert, Wilma, Allen, and Mitch were lower in pressure and all but Allen had lower wind speeds. Just curious

It also depends on the diameter of the eye wall. Smaller eye, same pressure, higher max sustained wind (supposedly measured just outside the eyewall). Larger eye, same pressure, lower sustained wind. It is just the conservation of momentum (figure skater spin) physics on a large scale.

Latitude, not yet. I think the hurricane hunters measure including with dropsondes, but NHC does not report transect results except as to extent of hurricane and TS winds from the eye. Is mostly info for their tracking models. Typhoon chaser Dad always said that if you want to know a cyclone track, you flew two complete transects, one parallel to present track and one orthogonal. Differential windspeeds on the track side will predict path. Makes perfect physics sense.
A true additional anecdote for long time WUWT commenters, just for color. He once took off from Guam as command pilot on an instrumented (dropsondes out the converted bombbay) B29 very early ‘hurricane hunter’. He barely managed the landing 24 hours later because the typhoon violence had bent his B29 tail 18 degrees out of true. Plane was scraped then and there for parts.
WW2 surplus, of no other value.

Right now…the NHC’s center is a hair below EYW…..we’re about 85 miles north….”if” by some miracle the NHC is right…….that’s why I’m trying to figure wind speed 50-70 miles out
…and can’t find anything on surge either…If it follows that track, south of us…it will empty the bay first

If I recall — and I was looking up into it at one point — Landsea told me that Gilbert’s eye at one point was a clearly defined 5 miles in diameter. When it made landfall in Cozumel (where I was) it had developed a double eye-wall – which resulted in an extremely long time period of the max sustained winds . . . what ever they were.

ristvan, you got me beat. In 1968 we took a heavy cruiser(U.S.S. Boston) through super typhoon Elaine and came out with the bow bent out by 7 degrees. During the worst we had a lot of time to think about the U.S.S. Pittsburgh and wonder if we were going to come out in two pieces like she did in WWII.

Living in the UK am more used to dealing with Atlantic lows rather then hurricanes.
But with Atlantic lows the strongest winds tend to be just to the south of the “eye of the storm”.
ls that the case with hurricanes as well ?.

High ground, reinforced concrete, he could easily have a bomb shelter good for 200 knots. He’s a billionaire and could afford an apocalyptic hurricane party. Probably showing Gone with the Wind at midnight…

Interesting idea “seed” to collapse the eyewall when it’s out in the Atlantic. I’m completely against the idea of hacking weather systems yet isn’t a hurricane off the coast of Africa a great opportunity to test the ability to collapse a potentially deadly weather event?

Hurricanes are low pressure systems feeding on water vapor from sea surface conditions?

I’m surprised that no one has really mentioned that Irma looked like she was an annular hurricane today, which is unusual in and of itself, but particularly interesting given the atmospheric and oceanic conditions. The white papers I’ve read hinted that annular hurricanes typically form with colder air aloft and cooler sea surface temperatures than Irma is experiencing.

Thanks Navarre, not good info though…
“Annular cyclones can maintain their respective peak intensities for extended periods of time unlike their asymmetric counterparts. Following peak intensity, such systems will tend to gradually taper off. This unusual intensity persistence makes their future intensities difficult to forecast and often results in large forecast errors. In an analysis of hurricanes in the East Pacific and North Atlantic between 1995 and 1999, Knaff and Kossin observed that the National Hurricane Center underestimated the intensity of annular hurricanes 72 hours out by 18.9 kn (35.0 km, 21.7 mph).[1]”

That sounds like one of the papers I read. However, I’m not sure how anything I’ve said contradicts the quotation. The quotation also states that annular hurricanes ‘can’ maintain peak intensity for extended periods of time, not that they ‘will’ maintain peak intensity.

I live on the south coast of England and our current sea temperature is only 17 Degrees C. Seems unlikely that would ever feed a hurricane, so having a very moderate climate (no snow in winter and usual max around 24C in summer) does have its advantages

Thanks, Tonyb. We will survive even though the weathef outcomes are yet to be dermined. No matter what, we were already prepared for the worst of all possible weather scenarios. Something most here learned before hit Cat 3 Willma 2005. As we did.

Note that, despite the millions of words from the experts, the majority of those tracks now are beginning to ease more easterwardly into the Atlantic off of the coast of Florida, rather than up through the middle of FL or up its eastern coast. Which is a good thing for wind damage, but it passes the hurricane’s strong winds and waves to the west after a long open ocean fetch. Which can increase waves and storm surge.

I just saw the projected wind speeds of Irma as it comes ashore in Miami – 145MPH, which
would be a Cat 4. Halfway up Florida, it looks to be 125 MPH and probably by the time it reaches the Carolinas it will be a Cat 2 or low Cat 3, barely achieving status of a major hurricane. It’s not even remotely close to the power of Camile 1969 (175MPH at landfall, gusts to 200MPH and pressure of 900MB.). Killed over 500 Americans.
Since records have been kept, only 3 made landfall in the U.S. as Cat 5 storms. Irwin will not join that group – it would have to have sustained winds of 157MPH to do so, and even that would make it a minimal Cat 5. storm. But, at least it is making landfall in the traditional way – hitting Florida.
They do call the University of Miami football team the Hurricanes, don’t they?

I guess I’m missing something. Was just looking at the NDBC sites closest to where Irma is now …. sustained speeds no greater than 55 knots, gust up to 78 knots …… none of which is anywhere near 185 mph according to the knots mph calculator. Storm at 2 pm AST … 18.5N 64.7w …. station at 18.34n 64.9.. which is only about 10 miles from the center of the storm.

Appears the eye is passing along north coast of PR, which isn’t really going to spare them much. Ground reports are oddly lower speed wind than NOAA and NWS, we have seen that with hurricanes before, though.

Puerto Rico lucked out. It went north of them. The bad part is in the NE quadrant…they are in the southern quadrant. Some Islands in the Bahamas are going to be hit really hard – those in the NE quadrant.
Let’s hope that it stays off the east coast of FL.